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Criteria for selecting a processor

Short answer

Key criteria include performance (speed, word length), power consumption, cost, on-chip memory and peripherals, interrupt handling, instruction set suitability, development tools, and availability. Real-time constraints and time-to-market also influence the choice.

Briefly explain the criteria for selecting a processor (microprocessor) in an embedded system.

Choosing the processor is a key design decision. The criteria are:

  1. Performance (speed): clock rate, MIPS, instruction cycle time and word length must meet the required response time or throughput.
  2. Word length (data width): 8, 16 or 32 bits, depending on the data precision and the amount of computation.
  3. Memory: amount of on-chip RAM and ROM/flash and the addressable space; external memory interface needed or not.
  4. Power consumption: low-power modes are vital for battery devices.
  5. Cost: unit price and total system cost, including peripheral chips.
  6. On-chip peripherals and I/O: timers, ADC/DAC, serial ports (UART, SPI, I2C), PWM, number of I/O pins; fewer external chips are needed.
  7. Interrupt handling: number of interrupt sources and latency for real-time response.
  8. Instruction set and architecture: suitability for the task (e.g. MAC for DSP, bit instructions for control); RISC or CISC.
  9. Development tools and support: compilers, debuggers, emulators, RTOS availability, programmer's familiarity, documentation.
  10. Availability and reliability: supply, vendor reputation, package size and operating temperature range.
  11. Time-to-market / reuse: existing software/IP and legacy code.

✓ Answer checked by Claude Opus 5.5 (high effort)

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